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      1 /*
      2  * Copyright 2012, The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *     http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include <llvm/ADT/Triple.h>
     18 #include <llvm/DerivedTypes.h>
     19 #include <llvm/Function.h>
     20 #include <llvm/Instructions.h>
     21 #include <llvm/IRBuilder.h>
     22 #include <llvm/Module.h>
     23 #include <llvm/Pass.h>
     24 #include <llvm/Type.h>
     25 #include <llvm/Target/TargetData.h>
     26 
     27 #include "bcc/AndroidBitcode/ABCExpandVAArgPass.h"
     28 
     29 #include "X86/X86ABCCompilerDriver.h"
     30 
     31 namespace {
     32 
     33 class X86ABCExpandVAArg : public bcc::ABCExpandVAArgPass {
     34 public:
     35   virtual const char *getPassName() const {
     36     return "X86 LLVM va_arg Instruction Expansion Pass";
     37   }
     38 
     39 private:
     40   // Derivative work from external/clang/lib/CodeGen/TargetInfo.cpp.
     41   virtual llvm::Value *expandVAArg(llvm::Instruction *pInst) {
     42     llvm::Type *pty = pInst->getType();
     43     llvm::Type *ty = pty->getContainedType(0);
     44     llvm::Value *va_list_addr = pInst->getOperand(0);
     45     llvm::IRBuilder<> builder(pInst);
     46     const llvm::TargetData *td = getAnalysisIfAvailable<llvm::TargetData>();
     47 
     48     llvm::Type *bp = llvm::Type::getInt8PtrTy(*mContext);
     49     llvm::Type *bpp = bp->getPointerTo(0);
     50     llvm::Value *va_list_addr_bpp = builder.CreateBitCast(va_list_addr,
     51                                                           bpp, "ap");
     52     llvm::Value *addr = builder.CreateLoad(va_list_addr_bpp, "ap.cur");
     53 
     54     llvm::Value *addr_typed = builder.CreateBitCast(addr, pty);
     55 
     56     // X86-32 stack type alignment is always 4.
     57     uint64_t offset = llvm::RoundUpToAlignment(td->getTypeSizeInBits(ty)/8, 4);
     58     llvm::Value *next_addr = builder.CreateGEP(addr,
     59       llvm::ConstantInt::get(llvm::Type::getInt32Ty(*mContext), offset),
     60       "ap.next");
     61     builder.CreateStore(next_addr, va_list_addr_bpp);
     62 
     63     return addr_typed;
     64   }
     65 
     66 }; // end X86ABCExpandVAArg
     67 
     68 } // end anonymous namespace
     69 
     70 namespace bcc {
     71 
     72 ABCExpandVAArgPass *X86ABCCompilerDriver::createExpandVAArgPass() const {
     73   return new X86ABCExpandVAArg();
     74 }
     75 
     76 } // end namespace bcc
     77